The drug regulatorsE.g., Food and Drug Administration (FDA) in the US, Central Drugs Standard Control Organization (CDSCO) in India, Therapeutic Goods Administration (TGA) in Australia, etc. in most countries require the drug companies to put an expiration date on all prescription and over-the-counter medications.
Now, drugs or medicines are basically separate chemicals mixed in certain proportions.
Once a drug is ready, researchers store it under recommended conditions (room temperature or refrigerated).
They keep checking it over time to see if its potency remains intact or if its chemical mixture breaks down.
But as researchers have other things to do, they can’t keep checking the same medicine for an indefinite amount of time.
So, they set a window that is usually between six months to two years.
Let’s say a drug was ready on 1 January 2021.
The drug company will check on it periodically till 31 December 2023.
If the compounds break down or the medicine seems ineffective by 30 September 2023, this date will become the medicine’s expiration date.
However, if the medicine is still potent and the compounds are intact on 31 December 2023, the drug company will make this date the expiration date and move to the next medicine.
This means the expiration date is simply the last point till which the company has data.
In 2017, a report was published that highlighted that many medicines remain effective years after their expiration date.
And aside from a handful of medicines that are rarely on the market, most common medicines do not become toxic after their expiration date.
It is just that they are not effective, and most likely, they will not have any adverse effects.
But since we can’t be sure (without lab tests), it is best not to take medicines after their expiration date.
For injections, eye drops, etc., the expiration date can also indicate the point till the medicine is likely sterile (not a breeding ground for bacteria).
